Interstate Highway System
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50 free Interstate Highway System trivia questions with answers — geography quiz, new questions added Oct 2026.
The Interstate Highway System is the backbone of American travel: tens of thousands of miles of freeway that changed where people live, work and take their vacations. It is also full of stories, from the politics behind its creation in the 1950s to the engineering feats, local battles and strange exceptions that shaped it. This quiz covers the whole network. Expect questions on the history of the system and the people who pushed for it, the logic behind the route numbers and signs, and the geography of the roads themselves: where the big routes begin and end, which cities and landmarks they pass, and which stretches hold the records. It suits road-trip fans, geography buffs, students reviewing postwar American history, and anyone hosting a trivia night. Every answer comes with a short explanation, so you finish knowing why the roads look the way they do.
30 of 50 questions with answers and explanations. Play the quiz
Q 01A stubborn urban legend says one mile in every five of Interstate must be straight to serve as what?
An emergency runway
An emergency runway was never part of the plan: no Interstate law has ever contained such a rule, however often the story is told.
Q 02Which president signed the 1956 law that launched construction of the Interstate Highway System?
Dwight D. Eisenhower
Dwight D. Eisenhower had crossed the country with an Army truck convoy in 1919, a 62-day slog that convinced him America needed better roads.
Q 03Which Interstate, running up the East Coast from Miami to Maine, crosses more states than any other?
I-95
I-95 crosses 15 states, yet until 2018 drivers had to leave it in New Jersey, where a planned stretch was never built.
Q 04On which Hawaiian island are all of the state's Interstates, including H-1, H-2 and H-3, located?
Oahu
Oahu's Interstates can never cross a state line. They were built to link the island's scattered military bases, including Pearl Harbor.
Q 05Which road, nicknamed the Mother Road, was officially retired in 1985 after Interstates replaced it?
Route 66
Route 66 got that nickname from John Steinbeck's novel The Grapes of Wrath, which follows Dust Bowl migrants heading west along it.
Q 06Under the Interstate numbering plan, main routes that run east to west are given what kind of number?
Even numbers
Even numbers mark the east–west routes, and they climb as you head north, from I-10 across the Deep South to I-94 along the northern tier.
Q 07Which country's motorway network, used by Allied armies in 1945, became a model for the Interstates?
Germany
Germany's Autobahn showed American commanders how quickly armies could move on wide, limited-access roads, a lesson they carried home after the war.
Q 08In Pixar's "Cars", the town of Radiator Springs fades after being bypassed by which Interstate?
I-40
I-40 drew the traffic away from towns like the film's. To research the story, Pixar animators drove the bypassed road in rented white Cadillacs.
Q 09Which president's wife championed the 1965 law that limited billboards and junkyards along Interstates?
Lady Bird Johnson
Lady Bird Johnson pushed so hard for the Highway Beautification Act that it was nicknamed Lady Bird's Bill. It also paid for roadside landscaping.
Q 10The Katy Freeway, a stretch of I-10 that reaches 26 lanes counting frontage roads, is in which city?
Houston
Houston's Katy Freeway is believed to be the widest in the world after a widening finished in 2008. It was first built in the 1960s with six to eight lanes.
Q 11Which Interstate, the longest of all, crosses 13 states from the Pacific Northwest to New England?
I-90
I-90 runs more than 3,000 miles, and for about 278 of them, across Indiana and Ohio, it shares its pavement with I-80.
Q 12Which three colors appear on the standard shield that marks every Interstate route?
Red, white and blue
Red, white and blue won a 1957 design contest: Texas Highway Department employee Richard Oliver's shield beat about 100 entries, and it is now a registered trademark.
Q 13What nickname is given to the toll stretch of I-75 that crosses the Florida Everglades?
Alligator Alley
Q 21Which early coast-to-coast road did the Army's 1919 truck convoy follow on its two-month crossing?
Lincoln Highway
The Lincoln Highway was so rough that the convoy averaged under 6 mph and broke dozens of wooden bridges along the way.
Q 22A three-digit Interstate whose first digit is odd, such as I-395, usually does what?
Branches off and never rejoins
A spur branches off and never rejoins. Start the number with a 2, 4, 6 or 8 instead and the road is a loop or bypass that meets its parent again.
Q 23I-55 follows the Mississippi River valley north from near New Orleans to which Great Lakes city?
Chicago
Alligator Alley began as an insult: the American Automobile Association thought the planned road would be useless to cars, a mere alley for alligators.
Q 14Which city buried its elevated stretch of I-93 in tunnels during the megaproject known as the Big Dig?
Boston
Boston's Big Dig became the most expensive highway project in the United States. A ribbon of parks, the Rose Kennedy Greenway, now covers the old route.
Q 15Which state has the most Interstate mileage, including nearly 880 miles of a single route?
Texas
Texas has more than 3,200 miles of Interstate, and its exit 880 on I-10 is the highest-numbered exit on any freeway in North America.
Q 16The phrase "inside the Beltway", shorthand for Washington politics, refers to which ring-road Interstate?
I-495
I-495, the Capital Beltway, is a 64-mile loop through the suburbs that touches the District itself only on a bridge over the Potomac.
Q 17Which tax did Congress choose in 1956 to fill the Highway Trust Fund that paid for the Interstates?
A gasoline tax
A gasoline tax of three cents a gallon fed the fund at first, so drivers paid for the new roads as they used them.
Q 18I-75 crosses which five-mile suspension span that links Michigan's Upper and Lower Peninsulas?
Mackinac Bridge
The Mackinac Bridge opened in 1957, ending the days when ferries were the only link across the straits. It is nicknamed the Mighty Mac.
Q 19Which Interstate is the only one to run unbroken from the Mexican border to the Canadian border?
I-5
I-5 follows the West Coast through Los Angeles, Sacramento and Seattle. Delegates from both neighboring countries attended the dedication of its final link.
Q 20Which Cold War word sits beside "Interstate" in the official name of the Interstate Highway System?
Defense
Defense reflects the network's military side: the roads are meant to speed troops between bases, airports and seaports as well as carry everyday traffic.
Chicago marks the northern end of I-55, which crosses the Mississippi River twice on its way up from the bayous.
Q 24Which Florida city marks the eastern end of I-10, the southernmost coast-to-coast Interstate?
Jacksonville
Jacksonville ends a road that begins beside the Pacific in Santa Monica, where a sign long proclaimed it the Christopher Columbus Transcontinental Highway.
Q 25Which 1973 event led Congress to cap speeds on every Interstate at 55 mph the following year?
An oil embargo
An oil embargo made saving fuel the goal, not safety. The national limit survived in some form until Congress repealed it in 1995.
Q 26Which state had no numeric daytime speed limit on its Interstates from 1995 to 1999?
Montana
Montana asked drivers only for a reasonable and prudent speed by day, until its Supreme Court threw the rule out as unconstitutionally vague.
Q 27Interstate traffic crosses Seattle's Lake Washington on what unusual kind of structure?
Floating bridges
Floating bridges, among the longest of their kind, carry the road on pontoons. The original one sank in a 1990 storm and had to be rebuilt.
Q 28The highest point on the Interstate System is a Colorado tunnel on I-70 that passes beneath what?
The Continental Divide
The Continental Divide runs above the tunnel, which tops out at 11,158 feet. Trucks carrying hazardous cargo must still climb over Loveland Pass instead.
Q 29Which U.S. territory has three Interstates on paper, though none of them carries an Interstate shield?
Puerto Rico
Puerto Rico's routes, labeled PRI-1, PRI-2 and PRI-3, exist for funding purposes only and are signed with ordinary island road numbers.
Q 30Which toll road, opened in 1940 with tunnels first dug for a railroad, became a model for the Interstates?
Pennsylvania Turnpike
The Pennsylvania Turnpike was the first long-distance controlled-access highway in the country. Six of its seven original tunnels had been started in the 1880s for a railroad that was never finished.